Dependent and independent variables.

Grand multiparity, defined as having five or more births, is a significant public health problem, especially in low resource settings where fertility rates are generally higher than in high-resource settings due to socio-economic factors such as poverty and low levels of women’s education, as well as disparities in access to modern contraceptives and advanced medical care. The study aimed to investigate the factors associated with grand multiparity in Zambia. The study analysed data from the 2018 Zambia Demographic and Health Survey (ZDHS) using a weighted sample of 13,683 women aged 15–49 years. Univariate analysis was used to present percent distributions of the selected background characteristics of women. Bivariate analysis was used to examine the association between selected background characteristics and grand multiparity. Multivariable logistic regression was then performed to identify factors of grand multiparity among women aged 15–49 years in Zambia. The prevalence of grand multiparity among women in Zambia was estimated at 24%. Women aged 25–29 years, 30–34 years, and 35 years or older had significantly higher odds of grand multiparity compared to women aged 15–24 years, with the highest odds observed in women aged 35 years or older (aOR=56.31, 95% CI: 11.626–272.780). Women with a first birth at age 25 years or older were 86% less likely to experience grand multiparity (aOR=0.14, 95% CI: 0.084–0.238). Higher education and wealth were protective factors, with women who attained secondary education (aOR=0.28, 95% CI: 0.182–0.418) and higher education (aOR=0.09, 95% CI: 0.046–0.174) having reduced odds of grand multiparity. Women from richer households were also less likely to experience grand multiparity (aOR=0.48, 95% CI: 0.337–0.701). Rural residence (aOR=1.46, 95% CI: 1.111–1.911) and contraceptive use (aOR=1.29, 95% CI: 1.074–1.545) were associated with increased odds of grand multiparity. Women with shorter birth intervals (less than 24 months) were almost three times more likely to be grand multiparous (aOR=2.74, 95% CI: 1.741–4.326). The findings underscore the complex interplay of socio-demographic factors in shaping reproductive patterns in Zambia. Strategies to reduce grand multiparity should consider promoting delayed marriage, increasing access to education and addressing rural-urban disparities in healthcare access and family planning services.